C function pointer simple use case, function pointer use case

C function pointer simple use case, function pointer use case

(1) function pointer:
Pointer to a function of the fixed parameter type and Return Value Type
Statement:
Int fun (int, int)
|
\/
Int (* pfun) (int, int)

Pfun is the function pointer (variable)

Call:

D = pfun (a, B );
E = (* pfun) (a, B );

##### Pointer Functions
Int * fun (int, int );
Int * (fun (int, int ));
#####

 

/* Ex01.c */
# Include <stdio. h>

Int max (int a, int B ){
Return (a> B? A: B );
}
Int min (int a, int B ){
Return (a <B? A: B );
}

Int main (int argc, char * argv []) {
Int (* pfun) (int, int );
Pfun = max;
Int a = 0, B = 0, c = 0, d = 0, e = 0;
Fscanf (stdin, "% d", & a, & B );

C = max (a, B );
D = pfun (a, B );
E = (* pfun) (a, B );
Fprintf (stdout, "% d \ n", c );
Fprintf (stdout, "% d \ n", d );
Fprintf (stdout, "% d \ n", e );
Return 0;
}

(2) define the type of the function pointer and declare the function pointer variable.
Typedef int (* Pfun) (int, int );

Pfun is the pointer type of a user-defined function.

Pfun pfun = min;

Create a Pfun variable and assign the min function to it.

 

/* Ex02.c */
# Include <stdio. h>

Typedef int (* Pfun) (int, int );

Int max (int a, int B ){
Return (a> B? A: B );
}
Int min (int a, int B ){
Return (a <B? A: B );
}

Int main (int argc, char * argv []) {
Pfun pfun = min;
Int a = 0, B = 0, c = 0, d = 0, e = 0;
Fscanf (stdin, "% d", & a, & B );

C = min (a, B );
D = pfun (a, B );
E = (* pfun) (a, B );
Fprintf (stdout, "% d \ n", c );
Fprintf (stdout, "% d \ n", d );
Fprintf (stdout, "% d \ n", e );
Return 0;
Return 0;
}

(3) You can pass a function as a parameter to another function.
# Include <stdio. h>

Typedef int (* Pfun) (int, int );

Int max (int a, int B ){
Return (a> B? A: B );
}
Int min (int a, int B ){
Return (a <B? A: B );
}

Int dofun (Pfun pfun, int a, int B) {// use the Pfun type function pointer variable pfun to receive incoming Functions
Return pfun (a, B );
}

Int main (int argc, char * argv []) {
Pfun pfun = min;
Int a = 0, B = 0, c = 0, d = 0, e = 0, f = 0;
Fscanf (stdin, "% d", & a, & B );

C = min (a, B );
D = pfun (a, B );
E = (* pfun) (a, B );
F = dofun (min, a, B); // input the min function as a parameter to dofun. dofun receives the function pointer of the corresponding type.
Fprintf (stdout, "% d \ n", c );
Fprintf (stdout, "% d \ n", d );
Fprintf (stdout, "% d \ n", e );
Fprintf (stdout, "% d \ n", e );
Return 0;
Return 0;
}

C function pointer example

Mxl033 is correct.
Void * func (void) is not a function pointer, but a function that returns a pointer. Is a function, not a pointer.

Typedef void (* pFunc) (); // function pointer type declaration, pointing to a function without returning any parameters.
Typedef int (* pFunc1) (int, int); // function pointer type declaration, pointing to return int type. The parameter has two int type functions.

Void func1 ()
{
Printf ("This is func1 \ n ");
}

Int add (int a, int B)
{
Return a + B;

}
Int main (void)
{
PFunc p = func1; // function pointer copy
P ();

// P = add; error, return type, and parameter do not match

PFunc1 p1 = add;

P1 (1, 2) // returns 3

Return 0;
}

The landlord can learn more slowly.

How to call C function pointers? How to use function pointers? An example is recommended.

Function: int fun (int a, int B );
To define a pointer to this function
Compare the pointer pointing to int;
Int * p; p = &;
How is p defined?
Make sure that p is a pointer type.
Write (* p ),
Then, consider the base type of p,
The base type of p is the int type of variable.
Put int in front of (* p ).
Int (* p );
Parentheses can be omitted, which is int * p;

Likewise
To implement pf = & fun;
(* Pf) define pf as a pointer,
Use the fun type as the base type of pf
Fun is equivalent to an int (int a, int B) type.
Int (int a, int B) (* pf );
The base type contains parentheses and brackets to be removed.
Int (* pf) (int a, int B); // brackets cannot be omitted
Pf = & fun;
Call time
(* Pf) (); pf () can both